In order to lower friction in the path of the filament loading to the MMU, I am stepping up the size of the tubes from 4 mm to 6 mm outer diameters. I was not able to find PC6-M10*1 pneumatic fittings, which would normally be used to fit 6mm tubing to the adapter vertigo235 designed, for a reasonable price. This is to give a similar push-to-connect interface for 6mm tubing as the pneumatic ones. It won't be air tight, but it is tight enough to feed the filament in correctly. An added bonus is that you can fit the tubes in one at a time instead of the juggling act of all at once like with the stock mmu.